I noticed the squares also, but several days ago. Gone now. My impression was that they were relevancy bars, too.
With the relevancy bar moved from the bottom to the side of the Adwords boxes, I saw one more advertiser's box in the right-hand column than I normally do before having to scroll down to see the rest. This may be a test to compress the column of AdWords boxes to make more of them visible at one time.
seasalt